For example, in a pressurized water reactor (PWR), light water is used as reactor coolant and neutron moderator to be high-temperature and high-pressure water that does not boil over the entire reactor internal, the high-temperature and high-pressure water is sent to the steam generator to generate steam by heat exchange, and the steam is sent to a turbine generator to generate electricity. Moreover, the steam generator is configured so that a plurality of heat exchanger tubes having an inverted U-shape is provided inside, end portions of each heat exchanger tube are supported by a tube sheet, and an inlet side channel head and an outlet side channel head of primary cooling water are formed at a lower end portion of a body portion. Further, an inlet portion of secondary cooling water is provided in the body portion to be located above a tube bundle shroud, a gas-water separator and a moisture separator are vertically arranged side by side, and a steam outlet is provided above the gas-water separator and the moisture separator.
As such a steam generator, for example, there is a steam generator described in Patent Literature 1 below.